Biology of the solitary wasp Trypoxylon (Trypargilum) agamemnon Richards 1934 (Hymenoptera: Crabronidae) in trap‐nests

Buschini, M.L.T. and Fajardo, S. 2009. Biology of the solitary wasp Trypoxylon (Trypargilum) agamemnon Richards 1934 (Hymenoptera: Crabronidae) in trap‐nests. —Acta Zoologica (Stockholm) 91 : 426–432. Some Trypoxylon species build their nests in preexisting tubular cavities like hollow stems and beetle borings in branches. Study of the biology of these insects is relatively easy because the females of these wasps nest with enormous success in trap‐nests. The aim of this study was to investigate the abundance, seasonality and life‐history of Trypoxylon agamemnon. For capture of these insects, trap‐nests were installed in the Parque Municipal das Araucárias in araucaria forest, grassland and swamp, from December, 2001 to December, 2005. Two hundred and ninety seven nests were obtained. They were constructed more often during the summer (from December to April). The nests were built only in araucaria forest and consisted of a linear series of cells, divided by mud partitions, whose number varied from 1 to 7. Normally they have only one vestibular cell. The inner cells had been provisioned, usually with spiders of Anyphaenidae family. Sex‐ratio was strongly female biased. Its main natural enemies included Chrysididae, Ichneumonidae and Tachinidae.     

Life-history and sex allocation in Trypoxylon (syn. Trypargilum) lactitarse (Hymenoptera; Crabronidae)

Hymenopterans have become a model for the study of factors that govern sex allocation. In 1983, Seger proposed a model to study Sphecidae wasps with a strong prediction that sex ratio for univoltine wasps should be 1 : 1 (female : male), and for partially bivoltine species it should be male-biased. The present study investigates if Trypoxylon lactitarse (Saussure, 1867) is a univoltine or a bivoltine species and if Seger's model prediction fits the pattern of sex ratio found in this species. The study was carried out at Parque Municipal das Araucárias, in the municipality of Guarapuava, state of Paraná, southern Brazil, from December 2001 to December 2004. Nests of T. lactitarse were obtained using trap-nests drilled longitudinally to a depth to 80 mm with 7.0, 10.0 and 13.0 mm opening diameter. They were placed in a very heterogeneous site filled with araucaria forests, swamps and grasslands. Trypoxylon lactitarse showed two alternative life histories: either they pupated immediately and emerged as adults later in the same season (direct development), or they entered diapause, overwintering and pupating the following spring (delayed development). Its annual sex ratios were not significantly different from 1 : 1, and both sex ratio of overwintering and sex ratio of direct-developing wasps were also not significantly different from 1 : 1, in all years of this study. By examining these results, it was possible to conclude that although T. lactitarse is a multivoltine species, with four generations per year and two alternative life histories, its sex ratio did not support Seger's model.     

Nesting biology of four species of Trypoxylon (Trypargilum) (Hymenoptera: Crabronidae) in Chaco Serrano woodland, Central Argentina

Trypoxylon (Trypargilum) (Crabronidae) wasps are solitary spider predators that can build their nests in artificial trap-nests, which enables study of their nesting architecture and biology. Twenty traps (each containing 15-30 internodes of cane) were placed in each of nine sites of Chaco Serrano Woodland in Central Argentina (Córdoba) in October 2005, and were recovered in June 2006. We obtained 91 nests of four species of Trypoxylon (Trypargilum). In the laboratory, each Trypoxylon nest was sectioned longitudinally to study its architecture. The number of brood cells was counted, and the occurrence and length of vestibular and intercalary cells and the pre-closing plug space were recorded. We measured the diameter of the cane entrance, total length of the nest, length of each brood cell, maximum thickness of mud partitions and closing plug thickness. We also recorded the cell contents: the wasps, their natural enemies and the prey spiders. Mortality was assessed and the sex ratio calculated for each species. Finally, the nests were examined to help clarify the function of the vestibular cell. The nest architecture was similar in the four species, with linear brood cells located one after the other separated by mud partitions, as in other species of the subgenus Trypargilum. Forty-eight percent of the nests had vestibular cells, but only two had intercalary cells. The thickness of the mud partitions and the length of the brood cells differed among species and were related to the size of the emerged wasp. The diameter of the nest entrance was directly related to the average length of the fore-tibia. Sex ratios of all species did not deviate from 0.5. Mortality due to parasitoids (Eulophidae; Melittobia sp.) was similar among species, while the mortality due to cuckoo wasps (Chrysididae) in T. lactitarse was higher than in the other species. The presence of vestibular cells was not related either to the mortality due to natural enemies or to the orientation of the trap in the field. Spiders in the family Araneidae were the most frequently collected prey.     

Nesting biology of Trypoxylon (Trypargilum) lactitarse Saussure (Hymenoptera, Crabronidae) in trap-nests in Southern Brazil.

This study was carried in the Parque Municipal das Araucárias in the municipality of Guarapuava, state of Paraná, Southern Brazil. Three hundred and sixty five nests of T. lactitarse were obtained using trap-nests of 0.7, 1.0, and 1.3 cm in diameter. All of them had similar architecture, regardless of the diameter of the trap-nest. Completed nests consisted of a linear series of brood cells whose average number per nest was of 3.3, 4.0 and 3.6 for the nests with 0.7 cm, 1.0 cm and 1.3 cm in diameter, respectively. They were constructed more often during the summer. T. lactitarse had two types of life cycles: direct development (without diapause), and delayed development (with diapause during winter). Natural enemies included Chrysididae, Sarcophagidae, Dolichopodidae and Ichneumonidae. Out of 1,353 identified spider prey, 1,313 belonged to the Araneidae family.     

The B chromosome system of Trypoxylon (Trypargilum) albitarse (Hymenoptera, Sphecidae) 1. Banding analysis

Karyotypic analyses of 366 specimens of the solitary wasp Trypoxylon (Trypargilum) albitarse collected from ten populations in the municipalities of Vi?osa and Porto Firme (Minas Gerais, Southeastern Brazil), revealed the presence of two morphological types of supernumerary (B) chromosomes. C-banding and fluorochrome banding suggest that the B chromosomes of T. albitarse may have originated from heterochromatin breaks within the standard (A) chromosome complement.     

Spider prey (Araneae) of Trypoxylon (Trypargilum) rogenhoferi (Hymenoptera: Sphecidae) in southeastern Brazil

Fifty five nests and 216 cells of Trypoxylon (Trypargilum) rogenhoferi were obtained from trap-nests (cut bamboo canes) in Santa Carlota Farm (Itaoca Section = IS and Santana Section = SS), Cajuru and on the S?o Paulo University Campus, Ribeir?o Preto (= RP), both in the State of S?o Paulo, Brazil (Sept. 1993-Oct. 1995). The prey (spiders) of 40 cells from IS, 58 from SS and 39 from RP were identified. The greatest nesting frequency occurred during the hot and wet season (September to April). T. rogenhoferi preyed upon individuals of five spider families, with Araneidae (orb-weaver spiders) being the most frequent (99.6%). Alpaida aff. negro (58%) was the most frequently collected species in IS, followed by A. alto (24.8%); in SS (59.6%) and RP (64.7%) the most frequent species was A. veniliae, followed in SS by A. aff. negro (14.9%) and in RP by A. leucogramma (13.5%). The size of reproductive niches, H' = 1.25 (IS), H' = 1.30 (SS) and H' = 1.29 (RP) were not significantly different. There was a positive correlation between the reproductive niche width (H') and evenness.     

Strongly female‐biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera,Crabronidae)

Buschini, M.L.T. and Bergamaschi, A.C.B. 2009. Strongly female‐biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera, Crabronidae). —Acta Zoologica (Stockholm) 91 : 433–439. This study was carried in southern Brazil from December 2001 to December 2004. The aim of this paper is to provide additional information on the life‐history and sex allocation of this little known species. This wasp’s species has two alternative life histories: either they pupated immediately and emerged as adults later in the same season (direct development) or they entered diapause, overwintering and pupating the following spring (delayed development). The numerical sex ratio of overwintering and of direct developing wasps were strongly female biased in 2002, 2003 and 2004.     

Imitate to integrate: reviewing the pathway for B chromosome integration in Trypoxylon (Trypargilum) albitarse (Hymenoptera, Sphecidae)

B chromosomes are genomic "intruders" normally characterized by their total dispensability counteracted by a variety of drive mechanisms, which assures their presence regardless of their harmful effects on the host genome. From an evolutionary standpoint, the relationship between standard (A) and B chromosomes can go through different pathways, from an everlasting arms race to a cordial B integration. Examples underlying the first situation are fairly common; B integration, however, has been more a theoretical than a practical possibility. The B chromosome in the haplodiploid solitary wasp Trypoxylon albitarse is probably the first example of a "mimetic" B, which is being integrated into the A genome by limiting itself to one B per haploid genome, the same dosage as the A chromosomes. Here we review some of the findings underlying this hypothesis and discuss the T. albitarse B strategy as a possible mechanism for B chromosome integration as a regular member of the chromosome complement in haplodiploid organisms.     

Diversity of mud-dauber wasps (Hymenoptera: Crabronidae: Trypoxylon Latreille) in a secondary forest of Trinidad,West Indies

Over a two-year period we operated two intercept traps for flying insects near and within a well-developed secondary forest in the Arima Valley of Trinidad. These yielded 368 Trypoxylon, representing 30 species. The sample’s Shannon–Wiener diversity of H′ = 2.61 is higher than that from a comparable study of Trypoxylon on the smaller island of Tobago (15 species, H′ = 2.09) and the even smaller Little Tobago (six species, H′ = 1.41). Analysis of the samples by the Chao1 method suggests that the species numbers recorded on the two smaller islands are complete, while there is at least one additional species at the Trinidad locality. The four most abundant species in our samples show no evident bias in numbers of females between the wet and dry seasons, consistent with the hypothesis that at least these species nest throughout the year.     

Nesting Biology of Microstigmus thripoctenus Richards, with a Study on Nest Recognition (Hymenoptera: Crabronidae)

In a study carried out on Microstigmus thripoctenus on Barro Colorado Island (Republic of Panama) between March and May 1998, 29 active nests were located. The nests contained between one and seven cells, with one (female) to six (three females and three males) adults. Using simple manipulations in which wasps were offered a choice between experimentally emptied foreign nests and their own nest when the adults were away, it was observed that returning adults were able to recognize their own nest. Foreign nests were always rejected by females coming from nests with a single adult, whereas individuals from nests with several adults in five of seven cases did accept the foreign nests, continuing their normal activities in them, without destroying their contents. Adopted foreign nests were inspected at a higher rate following adoption. Nests containing several adults tended to remain longer on leaves supporting them, and their external surfaces were inspected more frequently and longer than those of nests containing only one occupant. Nests are not associated with any particular plant and were found attached to leaves of 19 species of understory plants.     

Gene variation and genetic differentiation among populations of the solitary mud dauber wasp Trypoxylon (Trypargilum) albitarse Fabricius 1804 (Hymenoptera, Crabronidae)

Trypoxylon is a genus of solitary crabronid wasps whose populationgenetics is poorly known. The purpose of the present study was to investigate thegenetic variation and differentiation among five populations of Trypoxylonalbitarse, a species widely distributed throughout the Neotropics, withrecords from Panama to northern Argentina. Eight species-specific microsatellite lociwere used for genotyping 96 adult wasps (one female per nest) sampled at five sitesin Brazil. The analysis of allelic richness and private alleles indicated highgenetic diversity in the populations sampled. Pairwise comparisons using theF_st and D_est indices revealed significant differentiation for all, but one pair ofpopulations. F_st, D_est, AMOVA and assignment test values pointed to inter-population differentiation.Additionally, the analysis of population structure using Bayesian and PCA methodscharacterized two alternative genetic groups. The Mantel test indicated nocorrelation between genetic and geographic distances. Despite evidence ofconsiderable dispersal capacity for T. albitarse, the data indicatelow to moderate population structuring in this species.     

A new species of Quexua from southeastern Peru (Hymenoptera, Crabronidae)

A distinctive new species of the crabronine wasp genus Quexua Pate is described and figured from a single male collected from lowland Amazonian rain forest in southeastern Peru. Quexua cicrasp. n. is the only species in the genus known with a sessile metasoma.     

Mandibular glands of male European beewolves, Philanthus triangulum (Hymenoptera, Crabronidae)

Males of a solitary digger wasp, the European beewolf, Philanthus triangulum, possess large mandibular glands that have been reported to produce a scent marking pheromone. We analysed the morphology and ultrastructure of these glands using light microscopy as well as scanning and transmission electron microscopy. The paired glands are located laterally in the head and each side consists of a larger and a smaller part. Both parts possess a collecting duct each with distinct openings at the mandible base. However, the collecting duct of the larger part is additionally connected to the pharynx through a lateral extension. The collecting ducts are bordered by a monolayered epithelium lined with cuticle that exhibits conspicuous ramified protuberances. About 1400 acini consisting of class 3 gland cells surround the ducts and are connected to them through conducting canals. The main components in the cytoplasm of these gland cells are mitochondria, well-developed smooth endoplasmatic reticulum, and electron lucent vesicles suggesting a high secretory activity. The connection between the large gland parts and the pharynx suggests that the secretion of the mandibular glands might not only be delivered directly onto the mandibles but might also be transported to and stored in the postpharyngeal gland.     

Morphology of the male reproductive system and sperm ultrastructure of the egg parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera,Platygastridae)

Gryon pennsylvanicum is a platygastrid hymenopteran that has lately received increasing attention in Europe due to its possible use in biological control of the conifer seed bug pest Leptoglossus occidentalis. Here the male reproductive system and the spermatogenesis of this species, along with those of Gryon muscaeformis, are examined ultrastructurally for the first time. The male genital system is formed by a pair of testes, each containing only one follicle, a pair of accessory glands and deferent ducts connected to a single ejaculatory duct. All the stages of spermatogenesis are described in detail. Characteristic features of the Gryon spp. sperm, which are 100 μm long, are the presence of a polygonal nucleus, only one mitochondrial derivative, the occurrence of the centriole adjunct and a typical insect 9 + 9 + 2 flagellar axoneme. The single derivative, however, results from a process in which one of the two mitochondria is lost during spermiogenesis. Unlike in other insects, two centrioles occur in spermatids as a consequence of the ameiotic parthenogenesis. These characteristics stand as a valuable tool for phylogenetic inferences. Furthermore this study suggests a useful strategy for laboratory mass rearing.     

中国节腹泥蜂属一新种记述(膜翅目:方头泥蜂科)

记述采自中国海南省的方头泥蜂科Crabronniae、大头泥蜂亚科Philanthinae、节腹泥蜂属Cerceris 1新种:褐节腹泥蜂Cerceris rubigina,sp.nov..模式标本保存在云南农业大学昆虫标本室.     

Three new species and two new records of the genus Psen from China (Hymenoptera: Apoidea: Crabronidae)

Three new species of the genus Psen Latreille from China are described: Psen yunnanensis Ma et Li, sp. nov., from Yunnan Province; Psen lacuniventris Ma et Li, sp. nov., from Zhejiang and Sichuan Provinces; and Psen spinitibialis Ma et Li, sp. nov., from Zhejiang Province. Two species of the genus Psen are recorded from China for the first time. Modifications to the key to species of the genus Psen, as developed by van Lith in 1968, are presented.     

Morphology of the male reproductive system and sperm ultrastructure of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

The male reproductive tract of Leucoptera coffeella was processed for light and transmission electron microscopy. In the testis, the eupyrene cells are arranged in individual cysts, while the apyrene cysts form aggregates, never observed in other Lepidoptera. Both cysts contain 128 spermatozoa, which differ from the typical pattern. In the seminal vesicle, both types of spermatozoa are dispersed in the lumen, also different from other Lepidoptera. The apyrene spermatozoa are similar to those observed for other Lepidoptera. They present an anterior region covered by a dense cap and the flagellum is composed of a 9 + 9 + 2 axoneme and two mitochondrial derivatives. The eupyrene spermatozoa, however, differ from the typical pattern for Lepidoptera. Their anterior region contains a nucleus, an acrosome and a peculiar arc of eight accessory microtubules connected to the plasma membrane by dense bridges. In the nucleus–flagellum region, the ninth accessory microtubule is assembled between both mitochondrial derivatives, to participate in the axoneme. The flagellum comprises a 9 + 9 + 2 axoneme and two mitochondrial derivatives with paracrystalline cores. External to the plasma membrane and close to the accessory microtubules, there are tufts of an amorphous material, suggesting reduced lacinate appendages, while the reticular ones are absent. The reduction of lacinate appendages and the absence of sperm bundles in the seminal vesicle support the concept that the appendages of other Lepidoptera could be associated with the eupyrene aggregations. The characters ‘number of spermatozoa per cyst’ and ‘absence of bundles’ should be considered plesiomorphic, supporting the position of this taxon in the base of the Ditrysia.